Packers are commonly used in the oil and gas industry for drilling, intervention or well completion systems to provide a seal between the outside of production tubing and the inside of a wellbore wall, which may be open or include a casing or liner. A packer generally includes a sealing device, a holding or setting device, and an inside passage for fluids. Packer elements, i.e., a part of the sealing device, encircle the packing element cartridge and are designed to expand against casing or wellbore wall. The packing elements are commonly made of elastomers, which may limit their low and high temperature ratings as well as chemical resistance. Parts forming a packing assembly, i.e., the tools used in running and setting a packer, are designed to be mounted as separate parts in situ. This results in relatively complex assembly procedures and requires specialized personnel. Field re-dress, consequently, may become relatively difficult.
Due to the limited amount of expansion that packer elements are generally capable of, it is normal that packer elements of more than one size in outer diameter are necessary to seal casings of various weight ranges. Seal performance may also be improved using anti-extrusion parts, such as springs, or other low expansion backup systems to improve sealing. Accordingly, packer design may be weight range specific, requiring tool changes when the packers are run and set in various casing weight ranges. While expandable packing elements, such as inflatable, swellable and cup seals, are available for a wide range of seal bore sizes, they have relative low pressure ratings, limiting their application. In addition, such expandable elements may not be retrievable.
Therefore, room remains for the improvement of packing elements and packing element subassemblies, particularly in expandability, pressure rating, temperature rating, retrieve-ability and ease of use.